Switch and signal control system for railroads



S. N. WIGHT Oct. 29, 1940.

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Aug. 4. 1939 3 Sheets-Sheet 2 mvEgioRzu a ATTORNEY S. N. WIGHT Oct. 29, 1940.

SWITCH AND SIGNAL CONTROL SYSTEM FOR RAILROADS Filed Aug. 4, 1939 3 Sheets-Sheet 3 'INVENTOR I 6. 73. Z BY M Z; ATTORNEY Patented Oct. 29, 1940 I h 2,219,503 swrron AND SIGNAL CONTROL SYSTEM PATENT OFFICE FOR'RAILROADS SedgwickN. Wight, Rochester, N. Y., assignor to General 'Railway'Signal Company, Rochester,

ApplicationAugust 4, 1939, Serial No. 288,353

14 Claims. (Cl. 246-434) superimposed upon a line circuit is rendered dis-' v This invention relates to switch and signal con-, trol systems for railroads, and it more particularly pertains to an entrance-exit type of system for governingthe establishment of routes in a track layout remotely located from a control office. "-In a switch and signal control system of the entrance-exit type, a control machine having a control panel is provided at the control ofiice. Upon this control panel is a miniature track diagram corresponding to the actual track layout and disposed along such diagram are control buttons at points representative of the entrance and exit ends of each route. Each route is assumed to extend from an entering signal to another signal for governing trafiic in the same direction, or to some arbitrarily chosen point. To establish any desired route, an operatorhas only to designate the ends of such route by the actuation of the control buttons for the respective entranceand exit ends. Suitable indications are provided on the track diagram to keep an operator well informed as to the condition of occupancy ofithe various track sections, the routes established, and the clear and stop conditions of the signals. a

An object of the present invent is to so locate the: apparatus in an entrance-exit system that a minimum number of line wires is required between the control "office and the track layout for maintaining direct control of the field apparatus and-for'indications at all times. Thus, the designation of entrance and exit points at the control ofiice is communicated to the track layout over line circuitswhere route establishing means actsin accordance with such designation to set up a route between. the route ends which have been designated. The route establishing means provided at the track layout can be of a number of difierent types, one of which, for example, is shown in the patent to A. Langdo-n, Patent No. 2,148,865, dated February 28, 1939.

Another object of the present invention is to communicate over a single line circuit an entrance or an exit control to the track layout and to communicate an indication back over such line circuit as to the condition of the signal at such entrance point. The entrance and exit controls communicated over one line circuit are the respective entrance and exit controls for opposite directions of trafiic for a particular route end. Such controls are rendered distinctive by reason of the polarity used to energize the line circuit andthe corresponding response of a'polar neutral relay at the track layout. The signalindication tinctive 'from the entrance and exit controls by reason of a comparatively higth degree of energization of such line circuit, to which a marginal relay is responsive at the control ofiice.

In accordance with the usual requirements in entrance-exit systems, the system provided by the present invention includes an auxiliary means for the-establishment of, routes whereby each track switch is positioned in accordance with an auxiliary switch control lever at the control office. Such auxiliary switch control means is useful in freeing track switches'of obstructions such assnow and ice.

Another object of the present invention is to communicate indications over a single line circuit from the track layout to the'control oflice of the locked or, call for condition of all track switches included in a single detector track section, except when such track switches are locked or called for because their positions are defined by the auxiliary control of such track switches. Theactuation of an auxiliary switch'control lever atthe control ofiice for a particulartrack switch I causes the display of a locked or called for. indie I cation for that track switch, but for that track switch.only,irrespective of other track switches included withsuch track switch in one detector track sectiom I In other words, the establishment of aroute inaccordance with entranceandexit designation causes an indication to be transmitted overla singlelinefcircuit to the control ofilce for the illumination of theglockindi'cator lamps for.- eachrtrack switch included in a detector track sec:

tion in the route being set up; however, if such route is set up bytheabove mentioned auxiliary switch control means, only the lock indicator lamps becomeilluminatedfor the track switches which have their positions called for by their respective-, auxiliary switch control levers.

Thejcalled forflcondition of 'a track switch. as

used in;thi's description' is to be understood ,1 as meaning the selection of the normal or reverse. position-of such track switch by the energization of a switchcontrolzrelay inaccordance with'the' designationof entrance and exit ends of a route, or in accordance with the actuation to an. operate ingpositionrof theauxiliaryswitch control lever for suchtrack" switch.

-Another object ofxthe present invention is to provide that designation by an operator of both ends of a route toabe established isv initially essential, but. the establishment of a second-route having the-same entrance-point canbe effected upon designation of the exit point only for suchuroute.

Such mode of operation is effected because a relay responsive to entrance designation is maintained energized until manual restoration has been effected by an operator, while the route es- 5 tablishing means for each route is automatically restored to normal upon passage of a train. Therefore, upon passage of a first train, the route establishing means is restored, and the same route, or a conflicting route having the same en-- 10 trance point, can be established responsive to designation by an operator of the exit end of that route only, because the entrance end of that route is maintained defined until restoration for that entrance point is manually designated.

15 Other objects, purposes and characteristic features of the present invention will be in part obvious from the accompanying drawings, and in part pointed out as the description of the invention progresses.

30 In describing the invention in detail, reference will be made to the accompanying drawings in which corresponding parts are designated throughout the several figures by like reference characters, in which those parts having similar 25 featuresand functions are designated bylike letter reference characters which are generally made distinctive either by reason of preceding numerals or by preceding letter reference characters characteristic of the signal locations with which such 30 parts are associated, and in which-- Fig. 1 illustrates a miniature track diagram on a control panel together with control apparatus at a control ofiice;

Fig. 2 illustrates a route establishing means 10- 3'5 cated in the field responsive to entrance and exit controls designated at the control ofiice for setting up any desired route, and for clearing the signal governing entrance to such route; and

Fig. 3 illustrates the track layout in the field for which the system in this embodiment of the present invention is provided, together with various typical switch and signal control circuits.

For the purpose of simplifying the description I of the present invention, reference is made from 45 time to time to functions characteristic of a particular group of devices by use of letter reference characters common to such devices without their preceding numerals or letters representative of the signal locations with whichsuch 50 devices are associated. It is to be understood that such reference applies in general to parts designated in the drawings by letter reference characters which are similar except for preceding numerals, or letters representative of signal 10- 5'5 cations.

For the purpose of facilitating the disclosure of the present invention as to the mode of operation and the principles involved, the various devices and circuits constituting the embodiment of b the present invention have been shown diagrammatically and certain conventional illustrations have been employed rather than attempting to show the specific construction and arrangement of parts that would be employed in practice.

5 Thus, symbols are employed to indicate the connection to terminals of batteries or other sources of electric current instead of showing all of the wiring connections to those terminals, and relay windings and contacts are illustrated by conventional symbols, corresponding reference characters throughout the drawings being used to identify contacts provided on the same relay.

The symbols and are employed to H indicate the positive and negative terminals re- 7 spectively of batteries or other suitable sources of direct current, and the circuits with which those symbols are used always have current flowing in the same direction. The symbols (B+) and (B) indicate connections to the opposite terminals of a battery or other direct current 5 source which has a central or intermediate tap designated by (CN), and the circuits with which those symbols are used can have current flowing in one direction or the other, dependent upon the particular terminal used in combination with 10 the intermediate terminal (CN). The symbols (3+) and (B) shown associated with apparatus at the control ofifice are opposite terminals of a control office battery, and the symbols (3+) and (B) shown associated with apparatus at the field station are opposite terminals of a battery located in the field. A common wire (not shown) extends from the (CN) terminal of the control .office battery to the (CN) terminal of the hem station battery. If alternating current is to be used in place of direct current, the particular symbols employed represent the relative instantaneous polarities.

Track layout.With reference to Fig. 3, a track layout is illustrated for this embodiment of the present invention having a main stretch of track with two other tracks connected thereto by track switches 2 and 3 respectively. Inasmuch as the type of a switch and signal control system to which the present invention pertains is particularly adapted for use with complex track layouts, it is to be understood that the mode of operation and principles set forth in this disclosure for the control of the simple track layout illustrated in Fig. 3 are applicable to practically any complex track layout encountered in practice.

Trafiic through the track layout is governed by the signals A, B, C and D, signals A and B being provided for governing east bound traflic to the right and signals C and D being provided for governing westbound traffic to the left. Each of the signals illustrated is of the type having individual color lamp units, the upper unit containing a green lamp for a clear indication and the lower unit containing a red lamp for a danger indication. It is to be understood that a caution indication can also be provided if required in practice, and that other types of signals such, for example, as semaphore and search light signals can as well be used.

Each of the track switches 2 and 3 are power operated by a suitable switch machine which can be of the type shown, for example, in the patent to W. K. Howe, Patent No. 1,466,903, dated September 4, 1923, and the motor of the switch ma- '55 chine can be provided with overload protection and other features commonly employed in practice in a suitable manner such as that shown in the patent to'W. l-I. Hoppe et al., Patent No. 1,877,876, dated September 20, 1932.

A polar neutral switch repeater relay WP is provided for repeating the locked position of each of the track switches in correspondence with its respective switch machine in the usual manner. A relay WP is energized with one po- 5 larity when its switch machine and track switch are locked in a particular position and with the opposite polarity when such switch machine and track switch are locked in the opposite position. Each relay WP is dropped away whenever its 0 track switch and/or its switch machine are unlocked or out of correspondence with each other.

A detector track section T is provided in the usual manner, and the usualtrack circuit control (not shown) is provided for the track relay '7 TR associated with such detector track section. It is to be understood that the track switches 2 and '3 are properly bonded to provide-fouling protection in the usual manner. The relay TR governs a slow acting track repeater relay TP.

Control ofiice devices.-The miniature track diagram illustrated in'iFig. 1'is constructed on the control panel of the control machine at the control ofiice to correspond with the track layout illustrated in Fig.3 for which the system is provided. Disposed on the miniature track diagram at points representative of the respective entrance and exit ends of thevarious routes are entrance buttons NB and exit buttons XB. Thus, entrance buttons ANB, BNB, CNB and DNB are associated with entrance points defined at the track layout (see Fig. 3) by the location of signals A, B, C and D respectively. The exit buttons AXB, BXB, CXB and -DXB are used in designating exit points for routes having their exit ends at signal locations A, B, C and D respectively. The entrance buttons NB are of the rotary type having a normally closed contact, and another contact closed when the button is rotated to an operating position in which it remains until it is manually restored to normal by an operator. Such a control button can be constructed, for example, as-shown in the patent to J. F. Merkel, Patent No. 2,091,155, dated August 24, 1937. Each of the exit buttons'is of the push button type being self-restored to its normal position, and having a contact closed only when such button is depressed.

Although separate entrance and exit buttons have been shown for each of the route ends, it is to be understood of the entrance and exit buttons for each route end could as and that various distinctive operating positions for the buttons other than the specific positions provided in this embodiment of the present invention can be used in accordance with the requirements of practice.

Indications are provided on the control panel toxkeep an operator well informed as to thecondition of the routes established, the condition of occupancy of the various track sections and the condition of the signals. With reference to Fig. 1, an indicatorlamp TE is provided for indicating track occupancy, indicator lamps 2LE and SLE are provided for indicating the locked, or called for, condition of track switches 2 and 3 respectively, and signal indicator lamps AGE, BGE, CGE and DGE are provided within the entrance buttons N13 for the respective signals A, B, C and D, Other indicating means (not shown) is provided for indicating the correspondence of the position of each track switch with the position called for, and for indicating the position to which each track switch is operated. The correspondence indication is usuallyprovided by an indicator lamp located near the auxiliary switch control lever SML for that, particular track switch, and an indication as to the position of the track switch can be provided by a miniature switch point indicator, magnetically operated in accordance with the position of the polar contacts of the switch control relay WZZ (see Fig. 3) at the track layout. The switch point indicators and the correspondence lamps can be controlled, for example, inaccordance with circuits shown .in the patent to A. Langdon, Patent No. 2,121 ,803,

dated June 28, 1938.

' A marginal relay GP is provided at the control 17.5 office for governing each signal indicator lamp,

that the operating positionswell be combined into one button,

,lay NX for that particular route end is energized at the track layout with a polarity to cause its polar contacts to be operated to a right hand position. Such energization remains effective as long as the operator leaves the entrance button for thatentrance point in an operated position.

Each route end relay NX is also responsive 'to the designation of an exit point for that respective route end,- such relay being distinctively-energized under such conditions, only while the exit button XB for that route end is depressed.

An exit relay XR isprovided for each exit point, and it is responsive to the joint energize.- tion of relays NX for the respective entrance and exit ends'of a route having that point as exit. Each relay XR is maintained picked up dependent upon the relay NX for the entrance end of the'route and the entrance of a train into such route. Relays N, R, WZZ, L, LS, NCR, RCR and G are provided at the track layout for the proper establishment of routes and the clearing of signals responsive to the defining of the entrance and exit ends of each route, in accordance with principles which have been set forth for relays designated by similar reference characters in the above mentioned patent toA. Langdon, Patent No. 2,148,865, dated February 28, 1939.

A polar neutral relay WZ is provided at the track layout for each track switch for causing the positioning of such track switch in accordance with the actuation of the corresponding auxiliary switch control lever SML at the control office.

Having thus considered the apparatus 'pro- 1 vided in accordance with the present invention, the organization of such apparatus and the principles involved in its operation will hereinafter be considered by specifically describing certain typical operations.

Operation describing the present in that normal conditions of For the purpose of vention it is assumed the system exist when the devices at the control *office are in their nor-: mal positions as illustrated in Fig. 1 of the accompanying drawings, and the relays at the track layout are all in their de-energized positions as illustrated in Figs. 2 and 3 with the exception of the relays TR, TP, L, LS and NOR. The relays NCR are normally energized because it is assumed that the last route established through the track layout was a through route on the main track, thus requiring the track switches 2 and 3 to be operated to their respective normal posithe control buttons and tions. The relay TR is normally energized by the usual type of track circuit, and its repeater relay TP is normally energized by the closing of an obvious circuit at front contact'82 of relay TR (see Fig. 3). The relay L for each track switch is normally energized in accordance with the unoccupied condition of the detector track section with which it is, associated and the normally energized condition of route and approach lock-21.7

ing relays if the conditions in practice require such looking to be provided. Each relay L can be governed as is shown, for example, in the above mentioned patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939; In that patent each relay L is normally energized in accordance with the picked up position of the track relay for the detector track section with which it is associated, together with the picked up position of normally energized route locking stick relays for both directions of traffic. Each relay LS is normally energized by a circuit similar to the circuit closed for relay 3L8 from including back contact IU of relay 3WZ, front con tact I l of relay 3L, back contact l2 of relay 3WZZ, and winding of relay 3L8, to The relay NCR for each track switch is normally energized by a circuit similar to the circuit closed for relay 3NCR including back contact l3 of relay 3R, winding of relay 3NCR, polar contact M of relay 3WP in a right hand position, and front contact l5 of relay 3WP, to

At the control office the entrance buttons NB have their indexes in alignment with the arrows on the buttons to indicate that such buttons are in their normal positions, and each of the indicator lamps is extinguished to indicate that the track section is unoccupied by a train, and that each possible route through the track layout is available if an operator desires to establish such route.

To consider as a specific example of how a route can be established, assume that an operator desires to set up a route from signal B to signal D, and that he designates the ends of such route, at a time when the normal conditions of the system exist as they have been described, by the rotation of the entrance button BNB (see Fig. 1) in a clockwise direction to an operating position. Such operation causes the picking up of the entrance relay BNX at the track layout with its polar contacts operated to a right hand position because of the energization of a circuit closed from (B+), including contact l8 of but- 5 ton BNB closed when that button is in a clockwise rotated position, upper winding of relay BGP, upper winding of relay BNX, and lower winding of relay BNX, to (CN). The energization of that circuit does not cause the picking ,-50 up of relay BGP, however, because the lower ,55lng of relay BGP, to (CN).

winding of relay BGP is energized to neutralize the flux in that relay by a circuit closed from (B+), including contact l6 of button BNB in a rotated position, resistance l1, and lower wind- The resistance I1 is not required in the circuit just described if the lower winding of relay BGP is of proper design to neutralize the fiux in the magnetic structure of that relay.

, Upon designation of the exit point for the route from signal B to signal D, an operator by depressing the button DXB subsequent to the designation of the entrance point for that route, causes momentary energization of the relay DNX, with 5 such a polarity as to operate its polar contacts to a left hand position, by a circuit closed from v(B including contact E8 of button DXB closed in a depressed position, contact IQ of button DN'B closed in a normal position, upper winding 10 of relay DGP, upper winding of relay DNX, and

lower winding of relay DNX, to (CN). The relay DNX is picked up only so long as the button DXB is held in its depressed position, but the energization of that relay causes the picking up ;;75 of the exit relay DXR for that exit point and the subsequent establishment of a route between the entrance and exit points designated, in a manner hereinafter described. The relay DGP remains in a dropped away position when relay DNX is energized responsive to exit designation, because of the windings of that relay being connected in opposition as described when considering the designation of an entrance point. That is, the lower winding of relay DGP, connected in opposition to the upper winding of that relay, is energized by a circuit closed from (B), including contact I 8 of button DXB closed. in a depressed position, normally closed contact I9 of button DNB, resistance 20, and lower winding of relay DGP, to (CN).

Having thus considered how the designation of entrance and exit points for a particular route at the control oflice is defined at the track layout by the energization of an NX relay for each end of such route, it is to be understood that such modes of operation and circuits as have been described are typical of those employed in the designation of each of the entrance and exit points for each of the other routes.

Consideration will now be given to the means by which the self-selecting network is efiective to select the positions of the various track switches for the establishment of each route having its entrance and exit ends defined by the energization of relays NX for the respective entrance and exit points. Inasmuch as the route establishing means employed in this embodiment of the present invention is similar in many respects to the route establishing means shown and described in the patent to A. Langdon, Patent No. 2,148,865, dated February 28, 1939, and in the prior application of Wight and Langdon, Ser. No. 245,384, filed December 13, 1938. Many of the features of such route establishing means are not shown and described in detail in this disclosure as reference can be made to those prior disclosures for the specific description of such features.

In general, the defining of an entrance point, such as by the picking up of a relay NX with its polar contacts operated to a right hand position, causes the picking up of a relay Y for each track switch that can be trailed in a particular position (generally a normal position) upon passage of a train from the entrance point which has been defined. The picking up of such Y relays, in a general manner, preselects each route available emanating from the entrance point defined, and conditions a circuit for the energization of an exit relay XR for the exit end of each of such routes in such a manner that such exit relay can be picked up if the relay NX for that exit point is energized with its polar contacts operated in a left hand position.

After a relay XR, has been picked up in the establishment of a route, the normal and reverse switch control relays N and R for each track switch are selectively energized in accordance with the positions of the preselecting relays Y.

To consider more specifically the selection of the positions for the track switches in a route, assume that relay BNX (see Fig. 2) is picked up responsive to the designation of an entrance point at signal B in a manner which has been described, with its polar contacts operated to a right hand position. A circuit is then closed for the energization of relay ZY including front contact 2| of relay TR, front contact 22 of relay BNX, polar;

responsiveitorthe designationof an exit :point upon the depression of button DXB, relay DXR is picked up by the energization of a circuit closed from ,7 including front contact 2i of relay TR, 5 front contact 22 of relay BNX, polar contact 23 of relay BNX in a right hand position, back contact 24 of relay 2R, front contact 25 of relay ZY, back contact 26 of relay 3N, winding of relay mm, polar contact 21 of relay DNX in a left hand position, and front contact 28 of relay DNX, to The picking up of relay DXR. closes a stick circuit for that relay at front contact 29 to shunt contacts 21 and 28 out of the circuit just described and thus maintain relay DXR energized, dependent for deenergization upon. the dropping away of the relay BNX for the entrance end of the route being established.

When relay DXR is picked up, relay 3B is picked up bythe energization of a circuit closed from including front contact 30 of relay DXR, upper winding of relay 3R, and back contact 3! of relay 3N, to When that relay is picked up, relay 2N is picked up, because it is selected by the picked up position of relay 2Y, by the energization of a circuit closed from including front contact 39 of relay DXR, front contact 32 of relay 3R, front contact 33 of relay 2Y, upper winding of relay 2N, and back contact 34 of relay 2R, to v When relayBR is picked up, the switch control relay 3WZZ (see Fig. 3) is picked up by the energization of a circuit closed from including front contact I3 of 1relay3R, and lower winding of relay 3WZZ, to The picking up of relay 3WZZ due to such energization causesits polar contacts to be operated to a left-hand position and a circuit to be closed at front contacts 35 and 35 to apply proper polarity to the control wires for switch machine 3SM to cause the power operation of track switch 3 to a reverse locked position.

When relay 3B, is picked up in the establishment of a route from signal B to signal D, the correspondence relay 3NCR is dropped awat by the opening of a circuit for'that relay at back contact l3, and the dropping away of that relay closes a stick circuit for relay 3LS, for maintaining that relay energized until the switch machine 3SM has completed its operation, from including front contact 37 of relay 3L, back contact 38 of relay 3R-CR, ba'ck contact 39 'of relay 3NCR, front contact 40- of relay 3LS, and winding of relay 3L8, to When the track switch 3 has been completely operated to its reverse posiw 55 tion and locked, the relay 3WP is picked up with its polar contacts operated to a left hand position and the-correspondence relay 3RCR is picked up by the energization of a circuit closed from including back contact 4| of relay 3N, 60 winding of relay 3RCR, polar contact I4 of relay 3WP'in a left hand position,and front contact H"; of relay SWP, to c When relay 3RCR is picked up the stick circuit just describedfor relay 3LS is opened at 65 back contact 33 and relay 3L8 is dropped away because its normally energized circuit heretofore described is open at that time at back contact l2 ofrelay 3WZZ..

Upon the dropping away of relay 3L8, energy 70 is removed from the control wires of switch machine 3SM, and a branch of the control circuit for the signal control relay BG (see Fig. 2) is closed. I

Inasmuch as it is assumed that the track switch 2 is ina normal; position under normal. conditions,

the picking up of relay 2N causes the' picking up of relay 2WZZ (not shown) to cause the dropping away of relay ZLS by the opening ofla circuit for that relay (not shown) similar to the circuit described for relay 3LS. Thus, after the lock relay LS has been dropped away for each track switch included in the route being set up, a circuit is closed to cause the picking up of the signal control relay BG from including front contact 42 of relay DXR, front contact 43 of relay EH03, back contact 44 of relay 3NCR, back-contact 45 of relay 3L8, back contact 46 of relay 2L3, back contact 41 of relay ZRCR, front contact 48 of relay ZNCR, back contact 49 of'relay BXR, polar contact 50 of relay'BNX in a right hand position; front contact 5! of relay BNX, and winding of relay 3G, to The pickingoup of relayBG opens the circuit normally closed. for thered lamp in signal B at back contact 52 and closes a circuit for the green lamp in that signal at front contact 52, thus clearing the entering signal for a route which has been completely-set up from signal B to signal D. Y

To consider another specific example of how a route can be established through the track layout, assume that the normal conditions exist as they have been described except that the track switch. 3 is in a reverse position and that the correspondence relay 3RCR is energized (instead of relay SNCR) by a circuit which has been de- 5'- scribedn Such condition would exist after passage of a train over a route from signal. B to signal D. Under such conditions assume that an operator designates respectively entrance and exit points for a route .to be established from signal B to signal C.

The rotation of the entrance button BN'B for signal B causes the picking up of relay BNX (see Fig. 1) by the energization of a circuit'which has been described: and the picking up of that relay with its polar contacts operated to a right hand position, causes. the picking up of relay 2Y by the energization of a circuit which has also been described.

Upon depression of the exit button CXB subsequent to the picking up of the relays BNX and 2Y, relay CNX'ispicked up with its polar contacts operated to a left hand position in accordance with the energization of a circuit similar'to the one which was described for the energization of the relay DNX in accordance with the depression of button 'DXB at the control ofiice.

Upon the picking up of relay polar contacts operated to a left hand position in setting up aroute from signal B to signal C, relay CXR is picked up closed-from including front contact 2| of relay TR, front contact 22 of relay BNX, polar contact 23' ofrelay BNX in a right hand position,

back contact 24 of relay 2R, front contact 25 of relay 2Y, hack contact 53 of relay 3R, winding of relay CXR, polar contact 54 of relay CNX in a left hand position, and front contact 55 of relay CNX, to When relay CXR is picked up'a stick circuit is closed at front contact 56 to shunt contacts 54-and 55 out of the circuit just described. g

Upon the picking up of relay 'CXR relay 3N is picked up by the energization of a circuit closed from including front contact'51 of relay CXR, upper winding of relay 3N, and back contact 58 of relay 3R, to When that relay has picked up, relay ZNY is picked up by the energization of a circuit closed from including front contact 51 of rela CXB, front contact 59 CNX with its by the energization of a circuit its of relay 3N, front contact 33 of relay 2Y, upper winding of relay 2N, and back contact 34 of relay In accordance with the picking up of relay 3N, relay 3WZZ (see Fig. 3) is picked up with its polar contacts operated to a right hand position in accordance with the energization of a circuit closed from including front contact 4| of relay'3N, and upper winding of relay 3WZZ, to The closing of front contacts 35 and 3B of relay SWZZ with its polar contacts operated to a right hand position energizes the switch machine 3SM for operation of the track switch 3 to a normal position.

The relay 3LS is maintained energized during the operation of the switch machine 3SM because the relay SRCR is dropped away at that time on account of its circuit being opened at back contact 4| when relay 3N is picked up,-and the dropping away of that relay closes a stick circuit for relay 3LS which has been described, such stick circuit maintaining relay 3LS picked up until the complete operation of the track switch 3 has been effected to cause the relay 3WP to be picked up with its polar contacts operated to a right hand position, and thus cause the picking up'of the normal correspondence relay 3NCR by the energization of a circuit which has been described. The picking up of relay 3NCR. causes the dropping away of relay 3LS by opening the stick circuit for that relay at back contact 39.

Inasmuch as it has been assumed that the track switch 2 is in a normal position under normal conditions, relay ZLS (see Fig. 2) is dropped away as soon as the switch control relay ZWZZ (not shown) for track switch 2 is picked up in accordance with the energization of relay 2N. Thus, the dropping away of relay 3LS completes a circuit for the energization of the signal control relay BG closed from including front contact 60 of relay CXR, back contact 6| of relay SRCR, front contact 44 of relay 3NCR, back contact 45 of relay 3L5, back contact 46 of relay 2L8, back contact 4! of relay 2RCR, front contact 48 of relay 2NCR, back contact 49 of relay BXR, polar contact 50 of relay BNX in a right hand position, front contact 5| of relay BNX, and winding of relay BG, to

Having thus described as typical examples how the route establishing means is effective for the establishment of two different routes through the track layout, one route requiring the track switch 3 in a normal position and the other route requiring the track switch 3 to be in a reverse position, it is believed that it will be readily apparent to those familiar with the art how the system is effective for the establishment of each desired route in accordance with the entrance and exit ends designated for such route, a similar mode of operation being effective for both directions of trafllc.

It will be noted with reference to Fig. 2 that a separate circuit network is provided for the energization of the relay 3Y and the relays AXR and BXR from the circuits which have been described, as those relays are associated with the establishment of routes for west bound trafiic; however, it isbelieved that it will be readily apparent that the circuits for the control of such relays are provided in accordance with the general principles which have already been described.

The relays N and B- have separate windings of traffic, the circuits for the energization of the lower windings of such relays being provided for the establishment of routes for west bound traflic, conforming in principle to the circuits which have been described for the energization of the upper windings of such relays in the establishment of routes for east bound traflic. The circuit network forthe energization of the signal control relays G employs the same contact selections on the correspondence relays NCR and RCR and the lock relays LS for both directions of traffic over each route.

Upon considering the contact selections in the circuits which have been described for the ener'gization of the Y and KR relays, it will be apparent that the circuit network conforms to the track layout in the fact that it has branches corresponding to the various routes. The contact selections included in these branches provide that energy can flow through the network from the front contact of an entrance relay only through those branches which correspond with routes available to be established. It is therefore provided that each relay XR can be picked up responsive to the designation of the exit end of a route only when an available route can be established due to such designation. Such mode of operation prevents the preconditioning of a route. That is, if a route is not available at the time its route ends are designated, subsequent designation is necessary when the route is available before that route can be established.

As an auxiliary means of control for each of the track switches the switch control relays N and R can also be energized in accordance with the actuation of the auxiliary switch control lever for that track switch. Thus, for example, with reference to Fig. 1, the relay 3WZ is distinctively responsive to the energization of an obvious circuit closed at contact 16 of lever 3SML when that lever is actuated to a normal or a reverse operating position.

With reference to Fig. 3, the energization of relay 3WZ, at a time when the normal conditions of the system exist, in accordance with the actuation of lever 3SMIL to a reverse operating position, causes the polar contacts of relay 3WZ to be operated to a left hand position and a circuit to be closed for the center winding of relay 3R from including front contact I0 of relay 3WZ, polar contact 1! of relay 3WZ in a left hand position, center winding of relay 3R, and back contact 18 of relay 3N, to The picking up of relay 3R, due to the closing of that circuit, causes the operation of the track switch 3 to a reverse locked position in a manner which has been described.

If, on the other hand, the lever 3SML is operated to a normal operating position at a time when the normal conditions of the system exist, the relay 3WZ is picked up with its polar contacts in a right hand position to close a circuit for relay 3N from including front contact ill of relay 3WZ, polar contact 11 of relay 3WZ in a right hand position, center winding of relay 3N, and back contact 80 of relay 3R. to The picking up of relay 3N, due to the closing of that circuit, causes the operation of the track switch 3 to a normal position in a manner which has been described.

Indications.The indicator lamps on the control panel (see Fig. 1) are dark under normal conditions. If an operator rotates an entrance button from its normal position to an operating position in initiating the establ shment of a route, the signal indicator lamp GE (see Fig. 1) l included within that button is flashed by the intermittent energization of such lamp to indicate to the operator that such button is in an operating position, and that the signal for such corresponding entrance cleared.

To consider as a specific example how a signal indicator lamp isenergized when an operator designates an entrance point for a route to be established, assume that the operator rotates the entrance button BNB in a clockwise direction to an operating position. Such actuation of the'button causes the intermittent energization of the signal indicator lamp BGE' by a circuit closed from including back contact 62 of a coder CD, contact 63 of button BNB closed in a rotated position, back contact 84 of relay BG-P, and lamp BGE, to

As soon as the relay BG in the field is picked up for the clearing of signal B, after a route has been established between signal B and an exit point'which has been designated, the picking up of relay BG causes a higher degree of energization of the line circuit for the energization of relay BNX, because the closing of front contact 65 of relay BG shunts the lower winding of relay BNX out of the circuit which has been described by which relay BNX is initially energized in accordance with the designation of an entrance point at signal B by the rotation of button BNB; S-uch higher degree of energization causes the marginal relay BGP to be.

picked up by the energization of a circuit which has been described including the upper winding of that relay, and the picking up of relay BGP causes the signal indicator lamp BGE to be steadily energized because ofthe closing of an obvious circuit at front contact 64. Such steady energization of relay BGE of course indicates that the signal B governing entrance to the route established has been cleared.

' The lock indicator lamp LE for each track switch is illuminated whenever the position of a track switch is called for in the'setting up of a route (in accordance with entrance and exit designation) which is included in that particular detector track section. Thus, for example, the picking up of relay 3R-in the establishment of a route from signal B to signal D causes the picking up of the relay LTK at the control ofiice with its polar contacts operated to a left hand position, thereby causing the energization of the .lock indicator lamps HE and 3LEL The relay LTK is picked up under such conditions by the energization of a circuit closed from (3+), including front contact 66 of relay 3R, back contact 6'! of relay 3WZ. front contact 68 of relay TR, and winding of relay LTK, to (CN). The lamp 211E is illuminated upon the picking up of relay LTK by the energization of a circuit closed from including front contact 10 of relay LTK, normally closed con act H of lever ZSML, normally closed contact 12 of lever ZSML, and lamp ZLE, to Lamp 3LE is energized under such conditions by a circuit closed from including front contact 10 of relay LTK, normally closed contact 13 of lever 3SML, normally closed contact 14 of lever 3SML, and lamp SLEEJ, to I The track indicator lamp TE is deenergized except when track section T is occupied by a train to cause the track relay TR at the track layout to be dropped away and relay LTK to be picked up with its polar contacts operated to a right hand position by the energization of a cirbutton has not yet been cult closed from (B--.-), including back contact 68 of relay TR, and winding of relay LTK, to (CN). The energization of relay LTK with its polar contacts operated to a right hand position causes the track indicator lamp TE to be energizedby a circuit closed-from including front contact 10 of relay LTK, polar contact 15 of relay LTK in a right hand position, and lamp TE, to Inasmuch as the lamps LE are energized independent of the polarity by which relay LTK is energized, it is believed -to be obvious that such lamps are illumintated irrespective oflthe condition of occupancy of the detector track section. v

Although it is desirable that the lamps 2LE and 3LE be both illuminated whenever a route is established between any of the route ends in the track layout, it is also desirable that each lamp be illuminated individually when the auxiliary control lever SML for that track switch is operated from its normal position to a normal or reverse operating position. That is, the positioning of the track switch ZSML in accordance with the actuation of the auxiliary switch control lever ZSML causes the illumination of the lamp ZLE only.

To consider more specifically, how such general mode of operation is carried out, assume, at a time when the normal conditions of the system exist as they have been described, that an operator actuates the auxiliary switch control lever 3SML to acreverse operating position, and thus causes the auxiliary switch control relay 3WZ at the track layout to be picked up with its polar contracts operated to a left hand position by the energization of a circuit closed from (B-) including contact 16 of lever BSML in an upper position and winding of relay 3WZ, to (ON), The picking up of relay 3WZ with its polar contacts operated to a left hand position causes the picking up of relay 3R (see Fig. 3) by the energization of a circuit which has been described, but the picking up of relay 3R due to the energization of that circuit, however, does not cause the picking up of the indication relay LTK at the control oflice because the relay 3WZ is picked up to open the circuit described for relay LTK at back contact 61. However, at the control office, the-lamp 3LE is energized to correspond with the auxiliary switch control lever 3SML in an operating position by the energiza-tion of a circuit closed from through a circuit including contact 13 of lever 3SML in an upper position, contact 14 of lever 3SML and lamp. 3LE, to Under the conditions just described, the lamp 2LE. remains dark because the auxiliary switch control lever ZSML is in its center position, and the relay LTK is dropped away to open the circuit for that indicator lamp at front contact 10. Thus the lock indicator lamps LE are subject to group control except when an auxiliary lever for one of those track switches is in an operating position. Then each lamp in that group is energized in accordance with the position of the auxiliary switch control lever for that track switch.

From the above description it is believed to be obvious how lamp SLE is energized in accordance with the actuation of lever ESML to a normal operating position. Similar conditions exist with respect to the control of lamp ZLE.

Restoration to normaZ.-Having heretofore considered the conditioning of certain apparatus for the establishment of routes and for the clearing of signals, consideration will now be given to the restoration of such apparatus to the conditions which have been heretofore described as normal. In general, when a route has been established by designation of entrance and exit ends of such route, the route establishing means is maintained energized dependent for restoration, when the route is unoccupied by a train, upon the restoration of the entrance button NB for the entrance end of such route to normal. If such restoration is not effected prior to the entrance of a train into the route established, the passage of the train causes the automatic restoration of the route establishing means for the various track sections of the route as the train leaves each of such sections in passing from the entrance end of such route to the exit end. In otherwords, the passage of a train maintains the route established for track sections in advance of such train, and restores the route establishing means for the track sections in the rear of such train.

To consider more specifically how restoration is eifected when a route is unoccupied by a train, assume that a route is established from signal B to signal C, and signal B has been cleared, all in a manner which has been described. Also, assume, under such conditions, that an operator designates the restoration of such route by the rotation of the button BNB in a counterclockwise direction to its normal position, corresponding to the position illustrated in Fig. 1 with its index in alignment with the arrow on the button. Such restoration of the button BNB causes the relay BNX to be dropped away by the opening of the circuit for that relay at contact l6 of button BNB which is closed only when button BNB is rotated in a clockwise direction from its normal position.

When relay BNX is dropped away, the signal control relay BG (see Fig. 2) is dropped away by the opening of its circuit at front contact 5|, and the dropping away of that relay causes the green lamp in signal B to be extinguished and the red lamp to be illuminated, because of the opening of front contact 52 and the closing of back contact 52 respectively.

The dropping away of relay BNX also causes the dropping away of the relays CXR and 2Y by opening the circuits for those relays at front contact 22, and the dropping away of relay CXR causes relays 3N and 2N to be dropped away because of the opening of front contact 51. The dropping away of relays 2N and 3N causes their respective switch control relays ZWZZ (not shown) and SWZZ (see Fig. 3) to be dropped away.

The restoration of signal B to stop causes the energization of the lock relay 3L in accordance with general principles well known to those familiar with the art, and the picking up of relay 3L allows relay 3LS to be picked up as soon as the relay 3WZZ is dropped away to close a circuit for that'relay which has been described. In

. a similar manner relays 2L and ZLS (not shown) for track switch 2 are restored to their normal conditions, thus completing the restoraton to normal of all of the relays associated with the route which is assumed to have been established from signal B to signal C.

To consider how restoration is efiected automatically upon passage of a train, assume that a route has been set up from signal B to signal and signal B has been cleared, and that a train approaching signal B passes that signal and enters track section T. The dropping of track relay TR causes relay CXR to be dropped away by opening the circuits for that relay at front contact 2| (see Fig, 2); and the dropping away of relay CXR, causes the dropping away of relay BG by opening the circuit for that relay at front contact 60, thus causing the green lamp at signal B to be extinguished and the red lamp in that signal to be illuminated. The dropping away of relay CXR opens the pick-up circuits for relays 2N and 3N at front contact 51, but those relays do not drop away immediately as they are maintained energized by stick circuits .closed because of the presence of the train in the detector track section T. That is, the presence of the train in track section T causes relay 3L to be dropped away, and the dropping away of that relay closes a stick circuit for relay 3N from including back contact 31 of relay 3L, front contact 19 of I relay 3N, center winding of relay 3N, and back contact 80 of relay 3R, to In a similar manner, relay 2N is maintained energized de pendent upon the presence of the train in track section T. I

Relay 2Y is only momentarily dropped away, under the above conditions, as a pick-up circuit is closed for that relay upon the dropping away of the slow acting repeater relay TP at back contact 8|, connected in multiple with front contact 2! of relay TR in a circuit for relay 2Y which has been described.

As soon as the train leaves track section T, the stick circuit just described for relay 3N is opened at back contact 31 of relay 3L, and the dropping away of relay 3N causes relay 3WZZ to be dropped away by opening the circuit for that relay at front contact 4|. By similar mode of operation relay 2N is dropped away, and the dropping away of that relay causes the release of its switch control relay ZWZZ (not shown). Each of the lock relays LS for track switches land 3 respectively 5 is energized upon the dropping away of the relay WZZ for that track switch to complete the restoration to normal of the system associated with the establishment of a route from signal B to signal C, except for the relays BNX and ZY which remain in picked up positions in accordance with the clockwise operated position of button BNB at the control oifice. Thus, to complete the restoration of the apparatus associated with that route to normal, an operator must restore the entrance button BNB to its normal position. He receives an indication that such restoration is in order, because, the dropping away of relay BG at the track layout causes the signal indicator relay BGP to at the control office on account of the opening of the circuit by which it is picked up at front contact 65. The dropping away of relay BGP causes the indicator lamp BGE in button BNB to be flashed because of intermittent energization by a circuit which has already been described including back contact 64 of relay BGP.

An operator, however, is not required to restore the button BNB if he desires to set up a route for another train approaching signal 3..

Under such conditions, the operator has only to designate the exit end of the route he wishes to establish, as the entrance end of the route is already designated. Such exit end can be the exit end of any available route emanating from the entrance point which is defined by the energized condition of relay BNX, irrespective of the route last established through the track layout emanating from that entrance point.

Thus, as a specific example, assume that resbe dropped away.

toration has been effective as above described upon passage of a train from signal B to signal C, and that an operator-desires to set up a route for a following train from signal B to signal D after such automatic restoration has become effective. With button BNB remaining in its operated position, relays BNX and ZY are in a picked up position at that time, and the relay DXR (see Fig. 2) is picked up upon depression of button DXB in a manner which has been described. Responsive to the picking up of relay DXR, under such conditions, the relays 3B. and 2N are picked up, for the establishment of a route from signal B to signal D, and signal B is cleared, all in a manner which has been heretofore described.

By a similar mode of operation, an operator could establish a route from signal B to signal C for a following train after the preceding train has left that route upon the depression of button CXB at the control office. It is also provided that an operator can set up a route for a following train when the preceding train is still within such route. That is, when a train is occupying track section T in a route which has been established from signal B to signal C, a route can be set up for a following train from signal B to signal C upon the depression of the exit button C203. To consider more specifically how such mode of operationis accomplished, assume that a train has entered track section T upon passage over a route from signal B to signal C, and that signal B has been restored to stop because of the dropping away of the exit relay CXR. Upon depression of button CXB at the control office, re-

lay CNX is picked upat the track layout with its polar contacts operated to a left hand position and relay CXR is picked up by the energization of a circuit similar to a circuit which has been described, except that back contact 8| of relay TP connected in multiple with front contact 2| of relay TR closes the circuit instead of front contact 2| of relay TR. Responsive to the picking up of relay CXR, a route is established as has been heretofore described and relay BG is picked up to cause the clearing of signal B. If the train already in track section T leaves that track section before the following train accepts signal B, the route is maintained established because relay TP maintains relay CXR energized by a circuit closed at back contact 8! while relay TR is picked up to close front .contact 2| connected in multiple with back contact 8| of relay TP.

-Having described an entrance-exit system for governing the establishment of routes through a particular track layout as one specific embodiment of the present invention, it is to be understood that this form is selected to facilitate and simplify the disclosure of the present invention rather than to limit the number of forms which such invention may assume; and it is to be further understood that various adaptations, alterations and modifications may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention except as limited by the appending .claims.

What I claim is:

1. In a switch and signal control system of the character described, a track layout remotely located from a control office and having poweroperated track switches to provide various routes through the track layout between signal locations constituting entrance and exitpoints, a

control panel at the control office having manually operable contact means for said signal 10- cations operable to designate any given location as an entrance point or an exit point, a plurality of control line wires and a common return line wire extending from the control office to the track layout to form a line circuit for each signal location, circuit means effective to energize the line circuit for any given signal location with current of one polarity or the other in response to the actuation of the corresponding contact means to designate that'signal location as an entrance or exit point respectively, electro-responsive means at the track layout for each signal location distinctively responsive to the polarity of energization of the line .circuit extending to such location, and route establishing means at the track layout responsive only to the contemporaneous energization of both said electro-re-' sponsive means for the signal locations at the opposite ends of any given available route in accordance with the opposite polarities on their respective line circuits for effecting the power operation of the switches to, set up that given route and clear the signal at the location designated as the entrance end.

2. In a switch and signal control system of the entrance-exit type for governing the power-operation of the track switches in a remote track layout to establish the different routes between signal locations constituting entrance and exit points, a polar-neutral relay for each signal location constituting an entrance and/or exit point, a control panel in a control oflice having manually operable contact means for each of said signal locations operable to designate any given location as an entrance point or an exit point, a line circuit connecting the polar-neutral relay for any given signal location with its manually operable contact means at the control office, circuit means responsive to the actuation of said contact means for any given signal location'to energize the associated line circuit with current of one polarity or the other in accordance whether that signal location is designated as an entrance or an exit point, whereby the polarneutral relay for the corresponding signal location assumes distinctive positions, route establishing means responsive to the energization of both the polar-neutral relays to distinctive positions for the signal locations at the opposite ends of any given route to establish such route by causing the power operation of the appropriate track switches, and signal control means for clearing the signal at the entrance to any given route only provided the polar-neutral relay for that signal location is energized by current of the polarity applied upon an entrance designation for that signal location, and only provided the signal location for the exit end of that route has its polar neutral relay energized with the opposite polarity.

3. In a switch and signal control system of the character described for the establishment of each desired route extending through a track route remotely located from a control ofiice, such track layout providing by power switches a plurality of conflicting routes extending between entrance and exit points defined by the location of wayside signals at the route ends; manually operable contact means for each of the entrance and exit points; a polar relay for each route end which is common to the respective entrance and exit points at that route end for opposite directions of traffic; circuit means for energizing each of said polar relays with one polarity in accordance with the actuation of said contact means for an entrance point for that route end, and with the opposite polarity in accordance with the actuation-of said contact means for an exit point for that route end; and route establishing means responsive to the energization with opposite polarities of said polar relays for the opposite ends of each route for causing the power operation of the track switches to establish such route.

4. In a switch and signal control system of the entrance-exit type, a track layout remotely located from a control ofiice providing by a power switch a plurality of conflicting routes extending between entrance and exit points at the route ends, manually operable contact means for each of the entrance and exit points, a line circuit extending from the control office to the track layout for each route end, circuit means at the control oifice for energizing said line circuit with one polarity when said contact means is actuated for an entrance point for that route end and with the opposite polarity when said contact means is actuated for an exit point for that route end, a double-Wound polar relay at the track layout having both of its windings connected in series in said line circuit for that route end when said contact means for that route end is initially actuated, route establishing means in the track layout responsive to the contemporaneous energization with opposite polarities of said polar relays for respective entrance and exit ends of each route for causing the power operation of the track switches to establish such route, circuit means at the track layout for decreasing the resistance in each of said line circuits by shunting one of the windings of said polar relay for that route end, and electro-responsive means at the control office for each route end responsive to the increase in current flow in said line circuit for that route end.

5. In a switch and signal control system of the entrance-exit type, a track layout remotely located from a control ofiice providing by power switches a plurality of conflicting routes extendlocation of wayside signals; manually operable contact means in the control office for each of the entrance and exit points; a line circuit extending from the control oifice to the track layout for each route end; circuit means at the control ofiice for energizing said line circuit with one polarity when said contact means for an entrance, point at that route end is actuated, and with the opposite polarity when said contact means for an exit point at that route end is of each route for clearing the signal governing entrance to such route; circuit means responsive to the clearing of each signal for increasing the degree of current flow in said line circuit for that route end; and electro-responsive means in the control office in each of said line circuits energized only responsive to said increase in the degree, of energization of that line circuit, thereby indicating at the control ofiice the clearing of each signal at the track layout.

5. In a switch and signal control system of the entrance-exit type, a track layout remotely located from a control ofiice providing by power switches a plurality of conflicting routes extending between entrance and exit points at the ends of the routes, such points being defined by the location of wayside signals; manually operable contact means at the control ofiice for each of the entrance and exit points; a line circuit extending from the control ofiice to the track layout for each route end; circuit means at the control office for energizing said line circuit with one polarity when said contact means for an entrance point at that route end is actuated, and with the opposite polarity when said contact means for an exit point at that route end is actuated; electro-responsive means at the track layout for each route end distinctively responsive to the energization of said line circuit for that route end; route establishing means at the track layout responsive to the contemporaneous energization of said electro-responsive means with opposite polarities for the ends of each route for causing the power operation of the track switches to establish such route; circuit means for causing the current flow in each of said line circuits to be increased after the track switches have been properly positioned for the establishment of a route extending from an entrance point with which such line circuit is associated; and electro-responsive means at the control oiiice for each of said line circuits responsive only to an increase in current flow in such line circuit.

7. In a switch and signal control system of the character described, for the establishment by the power operation of track switches of each route extending between entrance and exit points through a track layout remotely located from a control ofiice, and for the clearing of a signal governing entrance to such route; manually operable contact means for each of the entrance and exit points; a line circuit extending from the control oflice to the track layout for each entrance point; circuit means for energizing said line circuit when said contact means is actuated for that entrance point; electro-responsive means in the track layout for each entrance point responsive to the energization of the line circuit for that point; route establishing means at the track layout responsive to the contemporaneous energization of said 'electro-responsive means for the entrance point for each route and the actuation of said contact means for the exit point for that route for causing the power operation of the track switches to establish such route; signalclearing means responsive to the establishment of each route for clearing the signal governing entrance to such route; means responsive to the clearing of each signal for increasing the current flow in the line circuit for that entrance point; and electro-responsive means at the control ofiice responsive to the increase in current flow in said line circuit.

8. In a switch and signal control system of the entrance-exit type for controlling the power operation of the track switches in a remote track layout to establish the various routes extending between signal locations constituting entrance and exit points and for the clearing of the signals governing such routes, electro-responsive means at the track layout associated with each of said signal locations and distinctively energizable for defining its signal location as an'lentrance or exit point, manually operable contact means in the control oflice for each of the signal locations operable to designate any given signal location as an entrance or an exit point, line circuit means associated with each of said signal locations for connectingthe electro-responsive means at the track layoutfor that signal location with the corresponding manually operable contact means in the control oifice for effecting the distinctive energization of said electro-responsive means in accordance with the designation of thatsignal location'as an entrance or an exit point upon the operation of such manually operable contact means, route establishing means at the track layout responsive to the energization of the electro-responsive means for both the entrance and exit points of any route for causing the power operation of the track switches as required to establish such route and for clearing the signal atthe entrance to such route, means responsive to the clearing of any signal for distinctively conditioning its associated line circuit means, means at the control oflice associated with each of said signal locations and responsive to the distinctive conditioning of the corresponding line circuit means to indicate when the associated signal is clear.

9. In a switch and signal control system of the entrance-exit type for the establishment of any desired route extending through a track layout providing by power switches a plurality of confiicting routes extending between entrance and exit points; manually operable contact means having normal and operating positions forv each of the entrance and exit points, such contact means for each exit point being self-restored to normal and for each entrance point being manually restored -to normal; electro-responsive means for each of the entrance and exit points; circuit means responsive to the actuation of said contact means for each entrance point for energizing said electro-responsive means for that point, such circuit means being efiective until said contact means for that point is restored to normal; circuit means responsive'to the actuation of said contact means for each exit point for energizing said electro-responsive means for that point, stick circuit means effective to maintain said electro-responsive means for each exit point energized, dependent for deenergization upon the entrance of a train into a route having that point as exit, such restoration of said electro-responsive means for each exit point being independent of said electro-responsive means for the entrance end of that route; route establishing means responsive to the contemporaneous energization of said electro-responsive means for respective entrance and exit points for each route for causing thepower operation of the track switches to establish such route, such route establishing means being maintained effective dependent upon the energized condition of said electro-responsive means for the exit end of that route.

10. In a switch and signal control system of the entrance-exit type for the establishment of each route extending through a track layout which provides by power switches a plurality of conflicting routes extending between entrance and exit points; manually operable contact means having normal and operating positions for each of the entrance and exit points, such contact means for each entrance point being manually restored to normal and for each exit point being self restored to normal; electro-responsive means for each of the entrance points; electroresponsivemeans for each of the exit points; circuit means for energizing said electro-responsive means for each of the entrance points when said contact means for that entrance point is actuated, such means being effective to maintainsaid electro-responsive' means for that entrance point energized, dependent for de-energization only upon actuation of said contact means for the restoration of that electro-responsive means to normal; circuit means for energizing said electro-responsive means for each exit point when the joint energization of said electro-responsive means for the entrance-and exit ends of each route for causing the power operation of the track switches to establish such route, such route establishing means being maintained effective only so long as said electro-responsive means for the respective entrance and exit ends of that route are both maintained energized; whereby it is required that said manually operable contact means be actuated for both ends of a route to be established for a first train, but the establishment of a route for a second train approaching the same entrance point after passage of the first train can be effected responsive to the actuation by an operator of said contact means for the exit point only of the route to be established for the second train, if said contact means for the entrance end of that route is maintained in an operating position.

'11. In a switch and signal control system of the entrance-exit type for indicating at the control oflice routes established at a track layout by the power operation of track switches between entrance and exit points; manually operable contact means at the control oflice for each of the entrance and exit points, a switch control lever at the control oflice for each of the track switches, route establishing means at the track layout responsive to the joint actuation of said contact means for the respective entrance and exit ends of each route'for causing the power operation of the track switches to establish such route; a detector track section at the track layout common to a plurality of track switches; switch control means at the track layout for each of the track switches distinctively responsive to the actuation of said switch control lever at the control ofiice for that track switch; an indicator lamp at the control ofiice for each of the track switches; an indicator lamp at the control oifice for said track section; circuit means including a line circuit extending from the control ofiice to the track layout for illuminating said indicator lamp for each track switch included in said track section when said route establishing means is effective to establish a route through that track section, such means being inefiective if the track switches in that track circuit are positioned in accordance with said switch control means; circuit means including said line circuit for illuminating said track indicator lamp at the control ofiice when said detector track section is occupied by a train;

' and circuit means at the control oflice for energizlng said indicator lamp for each track switch 12. In a switch, control system for railroads, a

track layout having power operated track switches to provide various routes extending be.-

tween locations at the opposite ends of the track layout constituting entrance and exit points for traific, contact means at a control ofiice for each of said locations manually operable to designate any given location as an entrance or exit point, electro-responsive means at the track layout for each of said locations constituting entrance and/or exit points, circuit means responsive to the operation of a manually operable contact means for any given location for distinctively energizing the associated electro-responsive means at the track layout in accordance with the operation of such contact means to designate that location as an entrance or exit point, and route establishing means controlled by the energization of the electro-responsive means for i: the locations at opposite ends of any given route for causing the power operation of the appro priate track switches to establish that route only providing the electro-responsive means at one end is distinctively energized to characterize an entrance point and the electro-responsive means at the opposite end is distinctively energized to characterize an exit point, whereby the manual operation of the contact means for the opposite ends of any route must properly designate the entrance and exit points of such route before any switch thereof is power operated.

13. In a switch and signal control system for a railroad track layout having power operated track switches to provide various routes extending between signal locations constituting entrance and exit points at the opposite ends of the track layout, a control panel having manually operable contact means associated with each signal location for designating that signal location as an entrance or an exit point, an entrance relay and an exit relay for each of said signal loca-- tions, circuit means responsive to the actuation of a manually operable contact means for any signal location to designate such location as an entrance point for energizing the associated entrance relay and maintaining it energized until said contact means is again actuated, circuit means responsive to the actuation of said contact means for any signal location to designate it as an exit point for energizing the exit relay for that location, stick circuit means for each of said exit relays efiective to maintain its relay energized dependent upon the energized condition of an entrance relay for the entrance point to a route terminating at such point corresponding to such exit relay and also dependent upon the unoccupied condition of the track section immediately in advance of such entrance point, and route establishing means acting to establish any given route in response to the energization of an entrance relay for one end of such route and an exit relay for the other end of such route and to clear'the signal at the entrance end of such route only providing said exit relay and said entrance relay are both energized, whereby the entrance of a train into an established route or another actuation of the contact means for the entrance end of an established route causes the restoration of the entering signal to stop.

14. Ina switch and signal control system for railroads, a track layout having power operated track switches to provide various routes extending between signal locations constituting entrance and exit points for traftlc, a control panel having manually operable contact means associated with each signal location for designating any signal location as an entrance or an exit point, an entrance relay and an exit relay for each of said signal locations, circuit means rendered efiective in response to the actuation of a manually operable contact means for any signal location to designate such location as an entrance point to energize the associated entrance relay and maintain it energized until said contact means is again actuated, circuit means responsive to the actuation of said contact means for any signal location to designate it as an exit point for momentarily energizing the exit relay for that location, stick circuit means for each of said exit relays efiective to maintain it energized dependent upon the energized condition of an entrance relay for the entrance point to a route terminating at such exit point as selected by contacts reflecting the positions of the switches in such route and also dependent upon the unoccupied condition of the track section immediately in advance of such entrance point, route establishing means acting to establish any given route in response to the energization of an entrance relay for one end of such route and an exit relay for the other end of such route, and to clear the signal at the entrance end of such route only providing said exit relay and said entrance relay are both energized, circuit means rendered effective upon the clearing of the signal at the entrance point to any established route and maintained effective upon the entrance of a train into such route for preventing the response of said route establishing means to the actuation of the manually operable contact means for any conflicting route irrespective of the release of the exit relay for said established route to automatically restore the entrance signal to stop upon the entrance of the train into such route, whereby any route may be established for a second train following the automatic deenergization of its exit relay by a first train merely by the manual actuation of the manually perable contact means for the exit end of such route, but said route can at any time be restored to stop by the actuation of the manually operable contact means for the entrance end of such route.

SEDGWICK N. WIGHT. 

